Hyponatremia associated with large-bone fracture in elderly patients.

Hyponatremia has been shown to be associated with gait disturbances, decreased mentation, and falls. The study objective was to determine the incidence of hyponatremia in patients who experienced a substantial skeletal fracture (hip/pelvis/femur). During an 18-month period from March 2007 to August 2008 serum sodium levels were evaluated in 364 cases of bone fracture in patients aged 65 years or older and in 364 nonfracture patients aged 65 years and older seen in an urban emergency room setting. The incidence of hyponatremia in patients with fractures was more than double that of nonfracture patients (9.1% and 4.1%, respectively; P = 0.007). The degree of hyponatremia was noted to be mild to moderate. Mean serum sodium of the entire fracture group was 131 +/- 2 mEq/L. In the fracture group the patients were 75.3% female, while females comprised 66.2% of the nonfracture group (P = 0.02). Of fracture patients with hyponatremia, 24.2% were taking antidepressants [3/4 of which were selective serotonin receptor inhibitors (SSRIs)], while none were taking these medications in the nonfracture group. Attention regarding careful follow-up of serum sodium levels in elderly patients seems appropriate.